Prior art infrared detectors are thermal detectors; they operate by absorbing incident electromagnetic radiation which is usually in the infrared region, centered around ten micrometers wavelength. Thermal detectors are sensitive to all wavelengths of radiation and are sometimes used to detect other wavelengths. A thermal radiation detector functions by absorbing incident radiation and converting the incident radiation to heat. The resulting temperature rise of the detector is then converted to an electrical signal. Any measurable temperature dependent material property may be used to sense the temperature.
The prior art has fabricated solid state infrared detector arrays which operate at room temperature, including pyroelectric and ferroelectric hybrid structures and monolithic bolometer arrays. The hybrid pyroelectric and ferroelectric arrays are fabricated in two parts, one part containing the infrared detector array, and the other part containing electronic circuitry to condition the detector signals and present them sequentially to a single output, forming a video signal. The monolithic bolometer array incorporates an array of bolometer detectors fabricated on micromachined thermal isolation structures called microbridges; the readout electronic circuitry is located on the microbridge substrate. This monolithic structure, in contrast to the hybrid arrays, may be fabricated using only thin film deposition and etching techniques.